Recently, in the manufacturing processes of semiconductors, in response to enhancement of the integration or performance of elements, there has been a demand for additional improvements in fine processing techniques. Among these manufacturing processes of semiconductors, etching techniques are one type of important fine processing techniques. Recently, among etching techniques, plasma etching techniques have been mainstreamed due to their capability of highly efficient fine processes of large areas.
Plasma etching techniques are one type of dry etching techniques. Plasma etching techniques are techniques in which fine patterns are formed in solid materials in the following fashion.
A mask pattern is formed on a solid material which is a process subject using a resist. Next, in a state in which the solid material is supported in a vacuum, a reactive gas is introduced into the vacuum, and a high-frequency electric field is applied to the reactive gas. Then, accelerated electrons collide with gas molecules and thus fall into a plasma state, and radicals (free radicals) generated from this plasma and ions react with the solid material, thereby producing a reaction product. In addition, this reaction product is removed, thereby forming a fine pattern on the solid material.
Meanwhile, as thin film-growing techniques in which raw material gas is chemically combined together through the action of plasma and the obtained compound is deposited on a substrate, there is, for example, a plasma CVD method. The plasma CVD method is a film-forming method in which plasma discharge is caused by applying a high-frequency electric field to gas including raw material molecules, the raw material molecules are decomposed using electrons accelerated by the plasma discharge, and the obtained compound is deposited. Reactions that are not caused by thermal excitation alone at a low temperature become possible in plasma since gas in the system collides with each other and is activated, thereby forming radicals.
In semiconductor-manufacturing devices in which plasma is used such as plasma etching devices and plasma CVD devices, in the related art, an electrostatic chuck device in which wafers can be easily mounted and fixed on a specimen table and be maintained at a desired temperature is used. This electrostatic chuck device includes, in the upper part, a ring member (focus ring) which surrounds the wafer-placing surface and is disposed at the outer circumferential edge of a wafer adsorption part.
However, in plasma etching devices of the related art, when plasma is radiated to a wafer fixed to the electrostatic chuck device, the surface temperature of the wafer increases. Therefore, in order to prevent the increase in the surface temperature of wafers, a cooling medium such as water is circulated in a base part for adjusting the temperature of the electrostatic chuck device so as to cool the wafer from the lower side.
For electrostatic chuck devices, techniques in which the uniformity of the temperature at the outer circumference of wafers is improved by providing second electrostatic adsorption means for adsorbing the focus ring to the outer circumference of the wafer are known (for example, refer to Patent Literature No. 1). In these techniques, second electrostatic adsorption means is provided, whereby the focus ring is adsorbed to an electrostatic chuck part with a force greater than the force that adsorbs wafers, and a cooling medium (cooling gas) is blown to the rear surface of the focus ring, thereby adjusting the temperature of the focus ring and making the surface temperature of the wafers uniform.
In addition, techniques in which gas-providing parts are provided to the wafer adsorption part adsorbed using the electrostatic chuck part and the focus ring and the temperatures of the wafer adsorption part and the focus ring are respectively and independently controlled, whereby the uniformity of the surface temperature of wafers are improved are known (for example, refer to Patent Literature No. 2). In these techniques, a protruding part is formed on the contact surface of the electrostatic chuck part which is in contact with the focus ring or the surface roughness of the contact surface is increased along the circumferential direction of the electrostatic chuck part, whereby the heat-transferring area in the electrostatic chuck part, which is formed by cooling gas, is increased and cooling gas is communicated between the electrostatic chuck part and the focus ring. In addition, in these techniques, a groove is formed on a part of the electrostatic chuck part which is in contact with the focus ring, whereby the diffusivity of cooling gas in the focus ring is improved.